This invention relates to electrostatographic imaging systems. More specifically, the present invention is directed toward a power supply for operation of a DC corotron in an electrostatographic machine.
DC corotrons, as defined herein, are charging means for depositing charge, i.e. ions, of a single polarity on a surface. In contrast, an AC corotron is one that deposits charge of both positive and negative polarity onto a surface even if in a fashion that the surface, when insulating, is charged to a net positive or negative potential.
Conventionally, a constant positive or negative polarity voltage is coupled to the coronode of a DC corotron. Most commonly, the DC corotron power supplies are devices that amplify and rectify an AC line source to achieve the high potentials (about 400 volts) needed to exceed corona threshold levels. Almost universally, the rectified line voltage is filtered by a capacitor prior to coupling the voltage to the DC corotron. The filtered voltage is basically a high, constant level voltage with a small AC ripple voltage (roughly 100-200 volts) impressed on it. These prior art power supplies are satisfactory but are subject to design pressures aimed at reducing cost, power consumption and ozone emission.